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Photocatalytic Hydrogen Generation over Natural Sepiolite and Palygorskite
  • Patrik Kopčan 1,2,   
  • Alexandr Martaus 1,   
  • Kamila Kočí 1,3,*

Received: 21 Jan 2026 | Revised: 20 Feb 2026 | Accepted: 11 Mar 2026 | Published: 19 Mar 2026

Abstract

Natural fibrous clays—sepiolite (SEP) and palygorskite (PLG)—were evaluated as sustainable photocatalysts for UV-C hydrogen generation from aqueous methanol solution. Native and 24 h pre-irradiated samples were characterized by gas quantification, FTIR, SEM, AAS, and zeta-potential measurements and compared with TiO2 P25. PLG showed significant activation after irradiation: UV-C exposure removed carbonaceous residues and rearranged surface –OH groups, thereby improving channel accessibility and increasing H2 evolution to values comparable to P25. In contrast, SEP hydroxylated more strongly after irradiation and formed robust hydrogen bonds that stabilized methanol-derived intermediates and temporarily suppressed activity, even though the crystal structure remained stable. The results show that SEP and PLG respond to UV-C through different surface chemistry mechanisms, rather than changes in the crystal lattice. PLG is activated by surface cleaning and reorganization of hydroxyls, while SEP is inhibited by stabilization of intermediates and excessive hydroxylation. Overall, fibrous silicates appear to be affordable, robust, and tunable photocatalysts whose performance can be controlled by surface cleanliness and hydration.

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DOI
10.53941/photocatalysis.2026.100002
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Volume 2, Issue 1
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Kopčan, P.; Martaus, A.; Kočí, K. Photocatalytic Hydrogen Generation over Natural Sepiolite and Palygorskite. Photocatalysis 2026, 2 (1), 2. https://doi.org/10.53941/photocatalysis.2026.100002.
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